Forging an understanding of Fe-based superconductors in the new Iron Age

University of Florida

The new iron-based superconductors have occasioned great excitement because transition temperatures are high, and it is hoped that the existence of a second class of such superconductors in addition to cuprates will lead to new insights into the essential ingredients for high temperature superconductivity. I will review what is known about the superconducting state and explain the basis for the near-consensus that almost all such materials display spin singlet, s-wave pair symmetry, but that the order parameter changes sign over the Fermi surface. The electrons that pair also possess an orbital degree of freedom, which plays an unusual role. High-Tc superconductivity in these unusual multiband materials poses anew the question of how higher temperature superconductivity might be achieved, and offers some new insights.